Sigma 50-500 mm f4.5-6.3 APO DG OS HSM Canon mount lens review: Modest price, good performanceBy Kevin Carter - Tuesday November 05 2013 Lens Review
As we’ve not yet analyzed the Canon EF 100-400mm f4.5-5.6L IS USM, the closest lens from Canon, we’ve taken the opportunity to compare this model with its forerunner, the slightly brighter 50-500 mm f4.0-6.3 Apo EX DG model. Although the current model was introduced with a price premium of around $200, it is a substantially better performer in terms of peak sharpness.
However, the earlier model had far less variation is sharpness throughout the zoom range. In most other respects the results were similar, though the new lens has notably lower levels of distortion.